[NFC] Fix builds on recent GCC with C++20 enabled

The following pattern fails on recent GCC versions with -std=c++20 flag passed
and succeeds with -std=c++17. Such behavior is not observed on Clang 16.0.

```c++
template <typename T>
struct Foo {
    Foo<T>(int a) {}
};
```

This patch removes template parameter from constructor in two occurences to
make the following command complete successfully:
bazel build -c fastbuild --cxxopt=-std=c++20 --host_cxxopt=-std=c++20 @llvm-project//llvm/...

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D154782